A COMPARISON OF FORAGE YIELD AND QUALITY IN A SIMULATED GRAZE-OUT FOR TWELVE VARIETIES OF HARD RED AND WHITE WINTER WHEAT

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1 Beef Cattle Research 2005 A COMPARISON OF FORAGE YIELD AND QUALITY IN A SIMULATED GRAZE-OUT FOR TWELVE VARIETIES OF HARD RED AND WHITE WINTER WHEAT R. L. Hale 1, C. T. Thompson 1, T. J. Dumler 1, and C. T. MacKown 2 Summary Six hard white winter wheat varieties (Burchett, Lakin, NuFrontier, NuHills, Nu- Horizon, and Trego) and six hard red winter wheat varieties (2137, Jagalene, Jagger, OK101, Stanton, and Thunderbolt) were planted in two southwestern Kansas counties, Clark and Stanton, to compare simulated graze-out forage yield and quality. Four replicated plots were planted in September 2003 for each variety at each location. Forage samples were collect from each plot during December 2003, March 2004, and April or May Dry matter content, dry matter yield, crude protein, acid detergent fiber (ADF), neutral detergent fiber (NDF), total digestible nutrients (TDN), net energy (NEm, NEg), relative feed value (RFV), and nitrate nitrogen were determined. Significant location-byvariety interactions were observed for most factors. Although significant differences in crude protein and energy were detected, it is unlikely that the performance of stock cattle would differ when grazing each of the varieties because the lowest crude protein concentration would support excellent gain, and because the differences in energy were relatively small. Introduction It has been estimated that as much as 6 million acres of winter wheat in Kansas are grazed during a good forage-producing year. Wheat pasture provides an economical, highquality forage for livestock during a time of year that few other grazable forage sources are available. Winter wheat can be grazed until the formation of the first hollow stem (jointing) without reducing grain yield. Dualpurpose wheat programs (forage and grain) permit producers to more effectively and profitably utilize their land. At times, producers will forgo a grain harvest and graze out the wheat to maximize profitability. Although hard red winter wheat varieties dominate, it is anticipated that the use of hard white winter wheats will increase substantially because of economic incentives associated with white wheat milling, end uses, and market opportunities. Kansas Agricultural Statistics Service reported increased white-wheat acres of 0.2, 0.8, 1.1, 2.7, and 4.9% of total wheat acres for the years 2000 to 2004, respectively, but research examining forage yield and quality of white wheat has been limited. This experiment examined the forage yield and quality in a simulated graze out of six popular hard white winter wheat varieties and six hard red winter wheat varieties. Procedures Six hard white winter wheat varieties (Burchett, Lakin, NuFrontier, NuHills, Nu- Horizon, and Trego) and six hard red winter wheat varieties (2137, Jagalene, Jagger, 1 Southwest Area Research and Extension Center, Garden City. 2 USDA ARS El Reno, Oklahoma. 35

2 OK101, Stanton, and Thunderbolt) were planted in two locations in southwestern Kansas, specifically in Clark and Stanton counties. Producers prepared the land and applied 65 lbs of nitrogen (Clark) or 80 lbs of nitrogen (Stanton) per acre before wheat planting. On September 16, 2003, each variety was planted in four replicated plots at each location in 10- inch rows at a depth of approximately 1.75 inches. The planting rates were 90 lbs seed per acre at the dryland Clark County plots and 120 lbs per acre at the irrigated Stanton County plots. Eleven lbs of nitrogen and 52 lbs of P 2 O 5 per acre were applied with the seed. Soil type at both locations was a silt loam. On March 26, 2004, liquid urea ammonium nitrate was applied at 30 lbs nitrogen per acre at both sites. Forage samples were collected on December 31, 2003, March 19, 2004, and April 29, 2004, at Clark County and December 30, 2003, March 25, 2004, and May 4, 2004, at Stanton County. Cuttings were collected from the same 6 feet of closely clipped row length in each plot. Samples were immediately dried at the Garden City Research and Extension Center and then sent to a commercial laboratory for analysis of crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF). Relative feed value (RFV), total digestible nutrients (TDN), and net energy contents (maintenance - NEm, gain - NEg) were calculated from the laboratory analyses. Nitrate-nitrogen assays were performed at the USDA-ARS laboratory in El Reno, OK. Data from the three cuttings were summed for statistical analysis. Results and Discussion Wheat varieties had different yields and compositions at the two locations, so values are presented for each variety at each location (Tables 1 to 4). A wide range in forage dry matter yields (3553 to 5672 lb/acre) was observed across 36 varieties at both locations. The varieties producing the most were Lakin, Jagalene, Trego, and NuFrontier at Clark County, yet they did not differ statistically from seven other location-by-variety combinations. Clark County tended to have more top yielding varieties than Stanton County did. Dry matter content differed from the greatest to the least by 5.4 percentage units. It is interesting that the 12 driest forages all came from Clark County, with Trego having the greatest dry matter content in Clark County, but having the least in Stanton County. Crude protein in the forage ranged from 17.9 to 24.0%. The eight variety/location combinations with the most crude protein ranged from 21.4 to 24.0%, and they were significantly different than the six with the least, which ranged from 17.9 to 19.7% crude protein. Seven of the eight variety/location combinations with the most crude protein were from Stanton. NuHills was the only variety in the top group from both locations. Acid detergent fiber (ADF), a measure of cellulose and lignin plant fractions, increases as a plant matures. Greater ADF is associated with lesser nutrient digestibility and energy availability. Acid detergent fiber ranged from 23.3 to 25.8% across all location-by-variety combinations, and was relatively evenly distributed across locations. Jagalene and Nu- Horizon in both counties, and NuHills in Clark County, had significantly less ADF than the five locations-by-variety combinations with the greatest ADF concentrations (Thunderbolt, Burchett, OK101, and Jagger in Clark County and Trego in Stanton County). Neutral detergent fiber (NDF) measures hemicellulose, cellulose, and lignin. As NDF increases, feed intake tends to decrease. Although NDF ranged from 43.5 to 48.8%, there was no location-by-variety interaction. Jagger, Stanton, Lakin, Thunderbolt, and OK101

3 all had greater NDF than Jagalene, NuHills, and NuHorizon did. Total digestible nutrients (TDN), related to digestible energy, ranged from 72.3 to 74.6%. Jagalene and NuHorizon in both locations had greater TDN than Jagger, Burchett, and OK101 had in Clark County or Trego had in Stanton County. Net energy for maintenance (NEm), ranging from 0.68 to 0.71 Mcal/lb, differed by variety only. NuHills, NuHorizon, and Jagalene had greater NEm than Jagger, Burchett, OK101, Stanton, and Thunderbolt had. Net energy for gain (NEg) concentrations ranged from 0.44 to 0.48 Mcal/lb. Jagalene at both locations and NuHills and Nu- Horizon in Clark County had greater NEg than Jagger, Thunderbolt, Burchet, Lakin and OK101 had in Clark County and Trego had in Stanton County. Relative feed value (RFV) is an index value calculated from ADF and NDF, and it is a quality-based factor commonly used in marketing of alfalfa hay. A greater RFV indicates that the forage is expected to yield greater animal intake and digestibility. RFV ranged from 135 to 153. NuHills, NuHorizon, and Jagalene in both locations had greater RFV than Jagger, Thunderbolt, Burchet, Lakin, and OK101 had in Clark County and Trego and 2137 had in Stanton County. Nitrate-nitrogen ranged from 101 to 527 ppm, with Stanton County varieties tending to have more nitrates. The greatest nitrates in an individual plot was 1503 ppm. All were less than Kansas State University s generally safe recommendation of 3000 ppm. The number of location-by-variety interactions makes it difficult to draw broad conclusions, but there seemed to be location differences in yield and quality factors that might be explained by differences in the stage of growth at the two locations. Clark County plots had somewhat higher yields but lower nutritional quality. Although the Stanton County location was irrigated and Clark County location was not, other factors such has a higher elevation and fewer growing degree units in Stanton County could have suppressed forage production. Stanton County forages may have been less mature and, therefore, slightly greater in nutritional quality. Although there was variation between locations, Jagalene tended to be a good yielder, and Jagalene, NuHills, NuHorizon, and Nu- Frontier tended to have greater energy concentrations, regardless of location. The varieties evaluated are among the more popular wheats planted, but they do not represent all wheat varieties. Also, our experiment did not evaluate all growing conditions or cultural practices. Factors not examined in our experiment will influence yield and quality. They include moisture, soil type, fertility, and management practices, and they should be considered when selecting a wheat variety for grazing or grain production. Cattle performance would be expected to be the same when grazing each of the different varieties because the least crude protein concentration would support excellent growth, and because the energy differences among varieties were relatively small. Variety differences between locations were most probably related to plant maturity, which would have more impact on nutritional content and stocker gain than the protein and energy differences observed in our experiment would have. 37

4 Table 1. Wheat Forage Dry Matter Yield and Dry Matter and Crude Protein Contents by and Variety Yield, lbs DM/acre Dry Matter, % Crude Protein, % Variety Variety Variety Variety Color Clark Stanton Mean Clark Stanton Mean Clark Stanton Mean 2137 Red 5282 cd 4130 ab cde 24.6 a abc 19.7 abc 19.5 Burchett White 4810 bcd 4614 bc efgh 25.0 a bcd 22.9 fg 21.4 Jagalene Red 5669 d 4585 bc fgh 25.1 a abc 24.0 g 21.7 Jagger Red 5256 bcd 3553 a cdefg 26.6 bc bcde 22.3 ef 21.4 Lakin White 5672 d 4474 b gh 25.3 ab a 21.0 bcde 19.5 NuFrontier White 5312 d 4301 ab cd 25.1 a bcd 21.4 def 20.7 NuHills White 4046 ab 3661 a cde 24.7 a ef 23.8 g 22.9 NuHorizon White 4742 bc 4864 bcd efgh 25.1 a bcd 22.0 ef 20.9 OK101 Red 4660 bc 3802 ab defgh 25.3 ab ab 20.5 bcde 19.8 Stanton Red 4945 bcd 4121 ab efgh 24.5 a bcd 20.9 bcde 20.4 Thunderbolt Red 5140 bcd 4480 b cdef 24.7 a bcde 22.8 fg 21.7 Trego White 5656 d 5156 bcd h 24.1 a a 21.0 cde 19.7 abcdefgh Means having differing superscripts within each measurement differ significantly (P<0.05). Table 2. Wheat Forage Acid Detergent Fiber, Neutral Detergent Fiber, and Total Digestible Nutrients by and Variety Acid Detergent Fiber, % Neutral Detergent Fiber, % Total Digestible Nutrients, % Variety Variety Variety Variety Color Clark Stanton Mean Clark Stanton Mean Clark Stanton Mean 2137 Red 25.0 cdef 25.0 cdef j 73.1 abcd 73.1 abcd 73.1 Burchett White 25.2 def 24.7 bcdef j 72.9 ab 73.4 abcdef 73.1 Jagalene Red 24.1 abc 23.3 a h 73.9 defg 74.6 g 74.3 Jagger Red 25.8 f 24.4 bcde jkl 72.3 a 73.7 bcdef 73.0 Lakin White 24.9 cdef 24.4 bcde kl 73.2 abcde 73.6 bcdef 73.4 NuFrontier White 24.2 abcd 24.4 bcde j 73.8 cdefg 73.6 bcdef 73.7 NuHills White 24.0 ab 24.4 bcde hi 74.0 efg 73.7 bcdef 73.8 NuHorizon White 23.7 ab 24.2 abc i 74.2 fg 73.8 cdefg 74.0 OK101 Red 25.2 def 24.9 cdef l 72.9 ab 73.2 abcd 73.0 Stanton Red 24.8 cdef 24.7 bcdef jkl 73.2 abcde 73.3 abcdef 73.3 Thunderbolt Red 25.1 def 24.4 bcde kl 73.0 abc 73.7 bcdef 73.3 Trego White 24.3 abcde 25.4 ef jk 73.8 bcdefg 72.7 ab 73.2 abcdefg Means having differing superscripts within each variable differ significantly (P<0.05). hijkl Overall variety means having differing superscripts differ significantly (P<0.05). 38

5 Table 3. Wheat Forage Net Energy Concentrations by and Variety Net Energy Maintenance, Mcal/lb Net Energy Gain, Mcal/lb Variety Color Clark Stanton Variety Mean Clark Stanton Variety Mean 2137 Red fg bcd abc Burchett White f abc bcd Jagalene Red h de e Jagger Red f a cde Lakin White fg abc bcd NuFrontier White fgh de bcd NuHills White gh de cde NuHorizon White h de cde OK101 Red f abc bcd Stanton Red f bcd bcd Thunderbolt Red f ab cde Trego White fg cde ab abcde Means having differing superscripts within each variable differ significantly (P<0.05). fgh Overall variety means having differing superscripts differ significantly (P<0.05). Table 4. Wheat Forage Relative Feed Value and Nitrate-Nitrogen Content by and Variety Relative Feed Value Nitrate Nitrogen, ppm Variety Color Clark Stanton Variety Mean Clark Stanton Variety Mean 2137 Red 142 cde 145 defg abcde 162 ab 196 Burchett White 141 bcd 144 defg abcde 312 cdef 258 Jagalene Red 150 hi 153 i a 527 g 329 Jagger Red 137 ab 143 cdef abcd 300 cdef 248 Lakin White 138 abc 143 cdefg a 278 bcdef 189 NuFrontier White 141 bcd 143 cdefg abcd 256 bcdef 227 NuHills White 146 efgh 147 gh bcdef 310 cdef 277 NuHorizon White 147 fgh 147 gh ab 296 cdef 219 OK101 Red 138 abcd 140 bcd abc 233 abcde 206 Stanton Red 139 abcd 142 cdef abcd 350 ef 272 Thunderbolt Red 135 a 144 defg abc 381 f 280 Trego White 145 defg 141 bcde abc 332 def 253 abcdefghi Means having differing superscripts within each variable differ significantly (P<.05). 39